Continuous flow centrifuge apparatus and rotor therefor



Jan. 15, 1963 Filed April 7, 1959 E. G. P CONTINUOUS FLO ICKELS ET AL W CENTRIFUGE APPARATUS AND ROTOR THEREFOR 4 Sheets-Sheet l FIG. -I

L :=L I H6 96 i 4 I K 7 Q *2 I I2 1 26 FIG. 6

EDWARD G. PICKELS RICHARD C. STALLMAN INVENTORS ATTORNEYS Jan. 15, 1963 E. G. PICKELS m-AL 3,073,517

c0NTINUous FLOW CENTRIFUGE APPARATUS AND ROTOR THEREFOR Filed April 7, 1959 4 Sheets-Sheet 2 O (O In LO 5 Aw I I N n I EDWARD s. PlCK ELS RICHARD c. STA/.LLMAN u.

mvEN'ToRs TTQPN Ys a Jan. 15, 1963 E. G. PiCKELS n 3,073,517

CONTINUOUEN FLOW CENTRIFUG ARATUS D ROTOR THEREF Filed April 7, 1959 4 Sheets-Sheet 3 EDWARD G. PICKE 7 RICHARD C. STALL 76 INVENTORS AT TORNEYS FIG. 4

1963 E. G. PICKELS EI'AL 3,073,517

CONTINUOUS FLOW CENTRIFUGE APPARATUS AND ROTOR THEREFOR 4 Sheets-Sheet 4 Filed April 7, 1959 EDWARD G. PICKELS RICHARD C. STALLMAN INVENTORS ATTORNEYS United States Patent Ofilice 3,673,517 Patented Jan. 15, 1963 3,073,517 CONTINUOUS FLOW CENTRIFUGE APPARATUS AND ROTOR THEREFGR Edward G. Pickels, Atherton, and Richard C. Stalhnan,

San Carios, Califi, assignors to Beckman Instruments,

Inc., a corporation of Caiifornia Filed Apr. 7, 1959, Ser. No. 804,609 Claims. (tCl. 233--32) The present invention relates generally to a centrifuge apparatus and more particularly toa continuousflow centrifuge apparatus and rotor therefor.

This application is a continuation-in-part of our copending application Serial No. 732,617, filed May 2, 1958, now abandoned.

In prior art continuous flow centrifuge apparatus the same to be separated is applied to rotors and is allowed to spill out of the separating chamber of the rotor into a collecting chamber from which the's'ample is removed by gravitational forces. The centrifugal forces cause the sample to attain relatively high velocities as it spills over into the collecting chamber. The result is that the sample breaks up into fine droplets which present a large combined surface area to the surrounding atmosphere; frothing, aerating, and denaturation of proteinaceous materials results.

In prior art apparatus having flexibly mounted rotors, it is difiicult to control the atmosphere within the centrifuge and to prevent bacterial contamination of the contents of the rotor. Prior art continuous flow rotors have a relatively large hold-up VOlurne making it impractical to operate upon small volumes of samples.

To resuspend the sediment which is collected in the prior art rotor surfaces during a separation is diflicult. It often involves manual scraping of the collecting surfaces.

It is a general object of the present invention to provide an improved continuous flow centrifuge apparatus and rotor therefor.

It is another object of the present invention to provide a continuous flow centrifuge apparatus and rotor therefor in which frothing, aeration and denaturation of proteinaceous materials is minimized.

It is a further object of the present invention to provide a continuous flow centrifuge apparatus which includes novel means for feeding the sample through the rotor and removing the sample from the rotor.

It is still a further object of the present invention to provide a continuous flow centrifuge rotor which has a separating chamber with a releasable core disposed therein so that the rotor has a separation chamber which is located at a distance from the axis of rotation whereby samples are subjected to large centrifugal forces. Yet the separation chamber has a relatively low hold-up volume. The core is releasable to resuspend the sediment.

These and other objects of the invention will become more clearly apparent from the following description when taken in conjunction with the accompanying drawmg.

Referring to the drawing:

FIGURE 1 is a side elevational view, partly in section, showing continuous flow centrifuge apparatus in accordance with the invention;

FIGURE 2 is an enlarged sectional view showing a continuous flow centrifuge rotor assembly and sample feeding and removing system;

FIGURE 3 is a sectional view taken along the line 3-3 of FIGURE 2;

FIGURE 4 is a sectional view taken along the line 4-4 of FIGURE 2; I

FIGURE 5 is a sectional view taken along the line 55 of FIGURE 2;

.held stationary by the arm 42 FIGURE 6 is a view schematically illustrating the flow of sample through the centrifuge rotor;

FIGURE 7 is a plan view of the sample feed and removal assembly support shown in FIGURE 2;

FIGURE 8 is a sectional view showing the rotor core released for resuspension of sediment;

FIGURE 9 shows the rotor mounted on a roller assembly for rolling the rotor t0 resuspend sediment; and

FIGURE 10 is an enlarged elevational view of a nut having a cut-away flange employed to hold the core positioning sleeve.

A centrifuge apparatus including an outer housing 11 which encloses the working parts is illustrated in FIG- URE 1. The top of the housing is provided with an opening '12 through which the rotor 13 may be passed for mounting on the drive shaft, as will be presently described. A sliding door 14 having alouvered opening 16 serves to close the opening 12 and provide access to the rotor chamber 15, to be presently described. The door 14 is provided with spaced rollers 17 which ride in spaced channels 18 secured to the sides of the housing 11. A latch mechanism (not shown) works in conjunction with controls (not shown) to releasably lock the door whereby it may be opened to install or remove a rotor from the rotor chamber 15. The louvered opening allows air to circulate through the rotor chamber, as will be presently described.

Theside walls of the rotor chamber are formed by a cylindrical member 19. The member 19 is made of relatively strong material and acts as a guard in the event of breakage or explosion of the rotor under the strains occasioned at the relatively high operating speeds at which it is operated. The louvers 21 carried in the louvered opening are slanted so that if breakage should occur, the pieces will not fly out of the chamber 15 and injure an operator.

The cylindrical member 19 is supported on a base 23 by a plurality of pins 24 secured to the bottom of the cylinder and to the base. The pins 24 serve to hold the bottom edge of the cylinder 19 spaced from the base 23 whereby air may circulate through the space between the cylinder 19 and the base 23. As the rotor 13 is rotated at relatively high velocity, it acts as a centrifugal pump pumping air outwardly through the space between the cylinder 19 and base 23. Air is continuously replenished through the opening 16 formed in the door 14.

The rotor 13, to be presently described in detail, is

-mounted on the end of a flexible drive shaft 26. The

lower end of the shaft is journalled in an oil filled bearing assembly 27. The bearing assembly is supported by the brackets 28 which extend downwardly from the base 23. A replaceable drive gear 29 is mounted at the lower end of the flexible shaft 26. The drive gear 29 is driven by a drive belt 31 which engages the driving pulley 32 of the motor 33. The motor is suitably mounted by brackets 34 to the base 23.

A removable plate 35 is carried onv the bottom of the rotor chamber to provide access to the drive gear 29. The drive gear and drive belt 31 are changed to operate the rotor at different speeds. Apparatus in accordance with the foregoing is described in detail in Patent No.

2,878,992, dated March 24, 1959.

A sample feed and removal assembly 41 is supported by an arm 42 mounted on an adjust-able post assembly 43 to be presently described in detail. A slot 44 is formed in the front edge of the door to accommodate .sample feed tube 46 and sample removing tube 47 connected to the sample feed and removal assembly 41, to be presently described in detail. The assembly 41 is and the rotor 13 rotates with respect thereto. A suitable sealing means 48, to be presently described in detail, may be employed to permit provision of an inert atmosphere to the rotor interior.

A rotor, sample feed and removal assembly, and support assembly are illustrated in detail in the enlarged sectional view, FIGURE 2. The rotor 13 includes a bowl 51 having cylindrical sides 52, a closed bottom 53, and an open top adapted to threadably receive a cover or lid 54. Recesses 56 and 57 are provided for receiving the pins of a spanner wrench for holding the rotor against rotation as the lid or cover is threaded to the upper portion of the bowl. An O-ring 58 rides against the shoulder 59 formed at the upper end of the inner surface of wall 52 to form a seal between the lid 54 and bowl 51. A mounting member 61 is formed integral with the bottom of the bowl and extends upwardly into the bowl. The mounting member 61 includes an axial opening 62 adapted to receive the upper (head) end of the driving shaft 26. A pair of spaced pins 63 are carried by the mounting member 61 and are adapted to seat in accommodating recesses (notshown) formed on the head of the shaft to provide a positive drive between the driving shaft and the rotor.

As described thus far, the rotor includes a relatively large chamber defined by the walls 52,.lid 54 andmounting member 61. A core '66 is placed in the chamber and occupies a large percentage of the volume of the chamber. The core 66 is cylindrical and may include spaced longitudinal grooves 67 formed in the outer surface 68. The diameter of the core is less than the diameter of the interior cylindrical surface 69 of the'walls 52 so that a small separating chamber .70 is formed. The outside surface and the upper and lower surfaces may be provided with a plurality of slots or grooves for feeding the sample to the separating chamber 70. By employing different cores 66, it is possible to form separating chambers of any desired volume.

The core 66 includes a central opening 71 which has a diameter greater than the diameter of the mounting member 61. A sleeve 72 is removably disposed between the opening 71 and the member 61. An O-ring 73 may be carried in a circumferential groove 74 formed in the mounting member 61 to assure a relatively good fit between the interior surface of the sleeve 72 and the member. The outer surface of the sleeve is provided with a groove 75 which accommodates an O-ring 75a. The O-ring rides against the inner surface 71 of the opening formed in the core 66 and forms a seal between the exterior surface of the sleeve and the interior surface of the core. The sleeve is provided with one or more longitudinal slots 76 which form fluid passages. The sleeve includes a rim 77 which in conjunction with the wall portions and the upper surface of the mounting means 61 forms a fluid sample feed chamber 78 adapted to receive the sample to be operated upon. The rim 77 defines a central opening 79 through which the feed tube 81, to be presently described, passes to extend into the chamber 78.

The upper end of the sleeve 72 is provided with a second groove 82 which receives the spaced portions 83 of a cutaway flange formed on a nut 84. The nut is threadably received by the lid or cover 54. The nut may be of the type shown in FIGURE 10. The sleeve 72 may be moved diametrically in and out of the nut. The sleeve is mounted in the nut and the assembly lowered into the rotor to center the core 66. The lower edge of the nut is accommodated in the circumferential shoulder 87 formed in the core 66. The nut 84 is provided with recesses 88 adapted to receive the pins of a spanner wrench. A groove 89 receives an O-ring 91 which forms a seal between the nut and the upper surface of the lid 54.

A sample removal chamber 93 is formed between the rim of the sleeve 72 and the interior of the nut 84. A plurality of openings 94 provides communication be- 'tween the chamber 93 and the channels 96 formed on Car ' grooves 67 are shallow at the top and bottom grooves communicate URES 2 and 4) formed in the sleeve. It is observed that the upper surface of the core 66. A suitable pump 100 is carried within the sample removal chamber 93 and serves to pump sample from the chamber upwardly through the annular space formed between the tube 81 and the tubular portion 102 of the pump 100. The sample flows outwardly through the outlet 103 which is associated with the sample removal tube 47. The tubular portion102 is carried within a head 105 and is held in place by an O-ring 104 carried in an internal groove 106.

The pump includes .a pair of spaced discs 107 and 108. The area between the discs communicates with the annular space through a plurality of openings 111, clearly illustrated in FIGURE 3. The pump operates in the following manner: The rotor is rotating at relatively high velocities, and as a result, the sample within the rotor is urged outwardly by centrifugal forces. It rides against the outer wall of 'the chamber '93 and forms a vertical wall offluid, illustrated at 116 in FIGURES 2 and 6. The rotational velocity of the fluid between the plates 107 and 108 .is reduced by its frictional engagement with the plates. Consequently, the centrifugal force and accompanying .pressure is reduced in this area. The high pressure exerted by the remainder of the fluid in the chamber 93, which fluid is at 'full rotor rotational ve locity, forces the sample inward between the plates through the openings formed in the pump and upwardly through the annular opening formed between the tube 81 and the tubular portion 102.

The core configuration is more clearly illustrated in FIGURES 3, 4 and v5. Referring to FIGURE 3, the upper surface of the core includes a plurality of radial grooves 96 which communicate with longitudinal grooves 67 formed on theperiphery ofthe core. Preferably, the 122 and 123 (FIGURE 2) and relatively deep in the central portion 124 of the .core. Components with a negative sedimentation ratewill then flow towards the center of the rotor and be collected within the central portion of the slot 124. The end portions 122 and 123 will act as a dam to retain the sediment. The lower portions of the slots connect to shallow radial grooves 126 (FIGURES .2 and 5) formed on the bottom of the rotor. These with the grooves or slots 76 (FIG- may be formed and that the sizes of the radial grooves 126, longitudinal grooves 67, and radial grooves 96 may be varied to accommodate different types of fluids and different feed rates.

A core of the type illustrated which includes a plurality of longitudinal grooves is preferable to a core which has a cylindrical outer surface. By employing a grooved core of the type illustrated, larger volumes may be accommodated with minimum rotational slippage of fluid in the separating chamber. The separating chamber is essentially broken up into a plurality of small longitudinal chambers in which circumferential flow or slippage of the sample is limited.

Referring to FIGURE 6, the flow path of the fluid is more clearly illustrated. Thus, a sample to be separated is fed from the vessel 131 through the tube 46 into the fluid feed chamber 78. It is seen that the fluid rides gently onto the vertical wall 132 formed by the fluid in the feed chamber under the influence of the centrifugal forces. Agitation and aeration are minimized. The wall 132 is formed by the centrifugal action of the rotating rotor. The fluid feeds outwardly down along the grooves 76 formed in the sleeve 72, outwardly along the grooves 126 formed in the bottom of the core 66, upwardly in the separating chamber or chambers formed between the vertical wall of the bowl and the core, radially inward along the grooves 96, into the fluid removal chamber where it forms a vertical wall 116 and is pumped upwardly and out through the tube 46 into the collecting vessel 133.

any number of grooves 76 Centrifugal forces cause the flow of sample from the feed chamber across the bottom of the core upward in the separating chamber, and out into the fluid removal chamber. This arises from the fact that where the sample is fed into the fluid feed chamber, the vertical wall 132 will have a smaller diameter than the wall 116 in the removal chamber, and as a result, there will be a pressure difference which causes the fluid to continuously flow through the rotor. This difference in head is present because of the frictional drag through the passages 96,

126 and separating chamber 71 The incoming fluid displaces the resident fiuid in the rotor toward the removal chamber 93.

The feed and removal assembly is supported by the arm 42 shown in FIGURES 2 and 7. The arm includes a yoke 14.7 which is adapted to ride within the circumferential groove 148 formed on the head 105. A clip 149 is adapted to move forward and lock the head 105 to-the yoke. A knurled screw 151 serves to lock the clip. The other end of the arm is provided with a collar 152 which rides on the adjustable sleeve 153 carried in the post 43. A locking screw 154 serves to lock the arm to the sleeve 153. The sleeve 153 includes a lower threaded portion which receives a nut 155 to provide an adjustment of the height. The nut is adapted to lock against the upper surface of the post 43. A securing bolt 153 passes through the assembly and is received by the base 35. Locating pins 159 may be provided for locating the post. In centrifugal apparatus, heavy particles acted upon by the centrifugal forces settle out and are packed against the outer wall of the separating chamber. It is then necessary to recover the sediment. One method which we have followed is to remove the nut 84 and sleeve 72 at the end of a run and then to remove the remaining sample through the threaded opening formed in the lid 54. Fluid suitable for mixing with the sediment is then introduced into the rotor. The nut 84 is then replaced. A suitable plug such as a cork 161 is then placed in the opening formed in the nut to seal the rotor.

The rotor is placed on its side with the central core member 66 riding against the lower surface. The sealed rotor is then placed on a rolling assembly which may be of the type schematically shown in FIGURE 9 which includes a driven roller 162. The roller 162 is driven from the motor 164 by a belt .163. An idler roller 165 is provided for supporting the rotor. The two rollers are mounted on the spaced plates 167 and 168 which include spacing members 169 and 171. By energizing the motor 164, the roller 162 is caused to rotate and the rotor 13 is driven on the idler roller 165. The rotor is continuously rotated. As the roller rotates, the central core member 66 bears on the bottom surface and tends to roll inside the rotor bowl. The liquid in front of the core is pushed ahead of the rolling core. The turbulent liquid erodes the sediment and resuspends it. The core may also slip giving rise to a scraping action.

As previously described, it is desirable in certain instances to provide an inert atmosphere to the interior of the rotor and to the sample being separated. An opening 171 is provided in the head 105, FIGURE 2, which opening extends downwardly and communicates with the interior of the rotor. A sleeve 172 is carried loosely on the outer surface of the head 105 and is spring loaded by a spring 173 whereby the same is urged downwardly. The lower surface 174 of the sleeve rides against the upper surface of the nut and serves to provide a seal. If desired, a suitable diaphragm 176 may be provided to enclose the spring and sleeve and to further seal the members. The inert atmosphere is introduced through the opening 171 and is maintained at a pressure slightly above that of the surrounds. Thus, the gas continuously leaks out and prevents entrance of air into the interior.

We claim:

1. A centrifuge rotor comprising a cylindrical bowl, a cover secured to the open end of said bowl, the interior surfaces of said bowl and cover forming a cylindrical chamber within the bowl, the outer surface of said chamber having a predetermined first radius, an axially disposed holding means extending into the chamber, a core disposed in said chamber, the outer periphery of said core defining a cylindrical surface of predetermined second radius less than the predetermined first radius, said core including an axial opening adapted to accommodate said axially disposed holding means, and a removable member normally disposed in the space between said axial opening and said holding means, said member having a minimum thickness which is greater than the difference between said first and second radii whereby upon removal of said memher the outer surface of the core can ride against the surface of the chamber.

2. A centrifuge rotor as in claim 1 wherein means threadably received by said cover removably engage the upper end of the member to permit removal of the member from the rotor.

3. A centrifuge rotor comprising a bowl having a bottom and a cylindrical wall, a cover secured to the upper end of the cylindrical wall to form a cylindrical chamber, an axially disposed mounting member extending upwardly from the bottom into the chamber, said member adapted to receive an associated driving means, a core disposed in said chamber, said core having a cylindrical outer surface and an axial opening, said cylindrical outer surface cooperating with the cylindrical wall to form a vertical separating chamber of predetermined thickness in the space between the outer surface of the core and the inside wall of the bowl, a removable sleeve having a minimum thickness greater than said predetermined thickness of the separating chamber mounted about said axially disposed mounting member and accommodated Within the axial opening of the core member to thereby normally maintain the core member coaxial within the bowl, means received by the cover extending into said chamber, the lower end of said means serving to removably engage the upper end of said removable sleeve to permit lifting of the sleeve from the rotor chamber to release the core so that it may ride against the wall of the separating chamber, a sample feed chamber disposed within the sleeve, a sample removal chamber disposed within the means received by the cover, means connecting the sample feed chamber to the bottom of the separating chamber, and means connecting the upper end of the separating chamber to the sample removal chamber.

4. Apparatus as in claim 3 wherein said means connecting the sample feed chamber to the bottom of the vertical separating chamber comprises longitudinal grooves formed in the inner surface of the sleeve, and radial grooves formed on the bottom of the cylindrical core.

5. Apparatus as in claim 3 wherein said means for removing sample from the separating chamber comprises radial grooves formed in the top of the cylindrical core communicating between the separating chamber and the sample removal chamber.

References Cited in the file of this patent UNITED STATES PATENTS 585,936 Linders July 6, 1897 732,886 Odell et al. July 7, 1903 2,139,715 Bergner Dec. 13, 1938 2,808,201 Mayeux Oct. 1, 1957 FOREIGN PATENTS 336,865 Great Britain Oct. 23, 1930 877,128 Germany Jan. 4, 1954 

3. A CENTRIFUGE ROTOR COMPRISING A BOWL HAVING A BOTTOM AND A CYLINDRICAL WALL, A COVER SECURED TO THE UPPER END OF THE CYLINDRICAL WALL TO FORM A CYLINDRICAL CHAMBER, AN AXIALLY DISPOSED MOUNTING MEMBER EXTENDING UPWARDLY FROM THE BOTTOM INTO THE CHAMBER, SAID MEMBER ADAPTED TO RECEIVE AN ASSOCIATED DRIVING MEANS, A CORE DISPOSED IN SAID CHAMBER, SAID CORE HAVING A CYLINDRICAL OUTER SURFACE AND AN AXIAL OPENING, SAID CYLINDRICAL OUTER SURFACE COOPERATING WITH THE CYLINDRICAL WALL TO FORM A VERTICAL SEPARATING CHAMBER OF PREDETERMINED THICKNESS IN THE SPACE BETWEEN THE OUTER SURFACE OF THE CORE AND THE INSIDE WALL OF THE BOWL, A REMOVABLE SLEEVE HAVING A MINIMUM THICKNESS GREATER THAN SAID PREDETERMINED THICKNESS OF THE SEPARATING CHAMBER MOUNTED ABOUT SAID AXIALLY DISPOSED MOUNTING MEMBER AND ACCOMMODATED WITHIN THE AXIAL OPENING 